Triac heating trouble

Hello ,

I have used optoisolator MOC3041 and triac BTA41-600BWG for switching a 2500W load.

The circuit is as below:


The triac heats up upto 117 degree Celcius which forces the circuit to get latched and remain ON forever.The traic burns up at around 130 degrees which is obvious.But the current flowing is actually just 9.7A with 230V AC supply.

Why is the circuit heating up?

What is the solution?

In the circuits given in several application notes the resistor Ra1 across gate and A1 terminal is not given but once I tried the same circuit which didnt work so I added the resistor and the switch worked well but its heating up.Does the resistor affect??

I believe there is some basic misunderstanding in my circuit but I'm unable to find it...:-(


Please help.

Thankyou in advance

Triac dissipate up around 40W at max load, but check datasheet. You need adequate heatsink its normal.

Use 330R resistors instead 100R.

tpetar said:

Triac dissipate up around 40W at max load, but check datasheet. You need adequate heatsink its normal.

Use 330R resistors instead 100R.

Click to expand...

I've already tried attaching heatsink.It just reduces time to heat up by few minutes.But the problem persists.

This triac at 35A dissipate 40W and at 10A something around 9W, for 40A you should keep temp under 70C. I think you didnt use appropriate heatsink or you forgot to put silicone paste between triac and heatsink. Check triac mounting on heatsink. Try with 330R resistors, replace both 100R with 330R.

Maybe you have bad or fake part as chinese suprising joke.